LIKE any recent Democratic presidential candidate, John Kerry’s hopes hinge on an overwhelming share of the black vote – about 90 percent. But Kerry’s hinge may be rusty.

The eye-opening poll came from Joint Center for Political and Economic Studies, the top Washington think tank on African-American issues. It found Kerry getting just 69 percent of the black vote – well below the 90 percent Al Gore received in 2000. And President Bush’s 18 percent doubled his 2000 share.

Bush owes part of his gain to the social conservatism of many black Americans. Blacks are more likely to oppose abortion and gay marriage than whites – that’s Bush’s side on both issues.

This week’s big Kerry rally in Philadelphia – where Bill Clinton spoke – was designed to help shore up Kerry’s support in the black community. Afterward, Kerry and Clinton did a conference call with African American ministers – and one of their key goals was to assuage the ministers’ concerns on gay marriage.

But Kerry’s problems with blacks go beyond simple issues. Discuss the candidate with African-Americans – even those likely to vote for him – and you’ll often hear that he is “distant” and “tone deaf.”

Look at what just happened in the key swing state of Ohio.

On Saturday, Oct. 16, Kerry gave a speech at a high school in the small town of Xenia, outside Dayton. Nearby is Wilberforce University – the oldest private historically black institution of higher learning, whose president is former Rep. Floyd Flake (D-Queens).

A rally, mainly of students from Wilberforce and its sister school, Central State University, was staged at the Wilberforce campus. Organizers were led to believe that if there were at least 100 people, Kerry’s motorcade would make a quick stop.

Eventually 150 students and supporters – including congressional candidate Kara Anastasio – gathered for four hours on a cold (rainy and snowy) Ohio day.

And the Kerry caravan drove right on by. All the long-suffering got from the candidate was a clenched “victory” fist out the window.

According to Shavon Ray, president of Wilberforce’s NAACP, the students were devastated – with comments such as “This is why I don’t vote.”

Ray told the local NAACP chapter the affair was a “slap in the face.”

After the incident – and Ray’s criticism – made the local paper, the Democratic Party sent one Ken Miller to Wilberforce to meet with Ray. He offered 50 tickets – and 8 VIP tickets – to a Kerry event in Dayton.

Ray declined what she saw as “hush tickets.” Taking seriously the idea that the NAACP is supposed to be non-partisan, Ray turned the tickets over to Wilberforce’s student government.

Next, Miller offered to have Rev. Al Sharpton stop by as a speaker. That annoyed Ray even more: “We don’t want a black face to speak to black students.”

The final straw was when Miller said Sharpton would be sent to speak to Central State University – along with X-rated rapper Foxy Brown.

When Ray reminded Miller that they didn’t want anything to do with Sharpton, Miller allegedly responded, “What do you want – Kerry to lose the f—ing race? We got you Al Sharpton. What more do you want?”

For Shavon Ray, it was simple: “The [campaign] could have just offered an apology and shared their sympathy to our school.”

Perhaps Kerry shouldn’t be held responsible for mistakes and intemperate behavior of the local Democratic organization. But Ray, fairly enough, says, “If you can’t handle this situation – which is minor – how are you going to handle the type of situations a president faces?”

She adds: “This is not acceptable. You can’t bypass us like we don’t even matter, like you have our vote pocketed and you don’t.”

“If people were thinking of voting for [Kerry], he could have lost it right there.”

Wilberforce has about 850 undergraduate students. As Ray says, “This is a small campus. Everybody hears about what is going on; everybody hears about something like this.

“The majority of students are registered to vote in Ohio. Others have their absentee ballots prepared.”

OK, it’s just 850 votes. But 537 votes swung Florida last time around.

Meanwhile, this past Wednesday, George W. Bush had a huge rally in the Pontiac Silverdome in the battleground state of Michigan. On stage with him were two of the most popular black gospel singers – Marvin Winans and Freeport, Long Island’s own Donnie McClurkin.